This invention relates to mechanical seals for pumps and the like and more particularly to split mechanical face seals.
Mechanical seals are used on a wide variety of machines, e.g., pumps, having rotating shafts that pass through housings, in order to prevent leakage of pressurized fluids. In one type of mechanical seal, the rotary face seal, sealing is achieved by arranging at least two rigid, durable sealing rings having extremely flat radially extending sealing faces axially adjacent each other and concentrically about the shaft so that the faces are in sealing contact. One ring is held stationary in the seal housing or gland while the other rotates with the shaft.
Repair or replacement of parts of such seals is difficult whenever inaccessibility of the outboard end of the shaft or the location of the machine make it impossible to slip the seal off the end of the shaft. In such situations, the machines themselves must be disassembled.
A solution to this problem has been to split the sealing rings and other seal parts radially into two or more parts so that each ring may be removed from, and new rings reassembled within, the seal and about the shaft, as disclosed in, e.g., U.S. Pat. No. 3,101,200.
Such split rings are manufactured, typically, by cutting a whole ring into two segments. With cut rings, the cut faces of one ring segment thereby created are precisely lapped while discarding the other ring segment and mating the one segment with a segment from another whole ring, similarly machined, so as to form a segmented ring of the same dimensions as a whole ring. Broken rings are also known in the art in which the irregular broken surfaces permit self matching of the ring halves without lapping.
In any event, precise alignment of the seal ring faces in such seals is achieved by lapping the backs as well as the faces of the rings, and then mounting them in holders, usually of metal. The holders, themselves, must be carefully lapped to receive the lapped backs of the rings. Then, the ring/holder assemblies are precisely aligned and rigidly held with respect to each other by pins, screws, dowels or the like.
An object of the present invention is to provide a split face seal which eliminates the need for expensive and time consuming precision alignment and lapping of seal ring surfaces other than the sealing surfaces themselves. Another object of the invention is to provide sealing functions in a split seal which are enhanced by fluid pressure.